CD8A and COVID-19: In the productive COVID-19 CD8 repertoires we found increased proportional usage of 10 V × J combinations, 4 of which used TRBV27, 5 of which used TRBV4-1, and none of which were significantly different in the non-productive sequences, indicating that the disease had selected for expansion of T cells expressing these TCRs (Fig. 5C and G).